<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Title</title>
</head>
<body>

</body>
<script>
	// (function(a,b,c){
	// 	console.log("fn",a,b,c);// fn 1 2 3
	// })(1,2,3);
	
	
	let userName = "zhangsan";
	(function(){
		let userName = "lisi";
		console.log(userName);// lisi
	})();
	console.log(userName);// zhangsan
</script>
</html>